Evaluation of Low-Dose Aldesleukin (ILT-101) on Regulatory T Cell Stimulation in Pediatric Autism Spectrum Disorder with Maternal Autoimmune Status

The primary objective is to determine whether a single subcutaneous dose of low‑dose interleukin‑2 (1.5 × 10⁶ IU aldesleukin; ILT‑101) administered on day 8 can stimulate regulatory T cells in children aged 4–6 years with autism spectrum disorder whose mothers experienced autoimmune disease during pregnancy, compared with placebo.

Secondary objectives include:

• Assessment of the clinical impact of ILT‑101 versus placebo on the Vineland‑II Adaptive Behavior Composite score at days 85 and 169, and evaluation of any persistent effect at day 275.
• Evaluation of the Vineland‑II sub‑scores for communication, socialisation, and daily living at days 85 and 169, with follow‑up at day 275.
• Examination of additional clinical dimensions—social cognition, repetitive behaviours, stereotypies, and hyperactivity—at days 85 and 169, and residual effects at day 275.
• Measurement of peripheral regulatory T cells and Th17 cells at baseline, days 8, 29, 85, and 169, and assessment of the correlation between these immunological markers and socio‑communicative symptoms at days 85, 169, and 275.
• Evaluation of tolerability and safety of ILT‑101 at baseline, days 8, 85, and 169.

The trial targeted children aged 4 to 6 years who met DSM‑5 criteria for moderate or severe Autism Spectrum disorder and whose mothers had experienced either an autoimmune disease or a documented infection during pregnancy; both male and female subjects were eligible. Participants were selected based on age, diagnosis, maternal exposure criteria, parental consent, and residence within the designated pediatric intervention area. General health status required the absence of conditions that could confound the evaluation of regulatory T‑cell stimulation. No specific dietary, physical activity, or habit requirements were imposed. The sponsor did not provide information on the total number of participants.

The study is a Phase 4, randomized, double-blind, placebo‑controlled trial evaluating low‑dose interleukin‑2 (ILT‑101) versus placebo in children aged 4–6 years diagnosed with autism spectrum disorder whose mothers experienced autoimmune disease or infection during pregnancy. Participants are screened for eligibility and, after informed consent, receive a baseline visit (Day 0) for clinical and laboratory assessments. The intervention consists of a single subcutaneous injection of 1.5 million IU aldesleukin on Day 8, with a follow‑up schedule including visits on Day 29, Day 85, Day 169, and Day 275, the latter serving as the end‑of‑study assessment. Primary efficacy is the change in regulatory T‑cells (Tregs) between baseline and Day 8; secondary outcomes encompass adaptive behavior, social cognition, repetitive behaviors, and safety measures collected at the scheduled visits. Individual involvement spans approximately 9 months from screening to end of study. Early termination may occur if a participant experiences a serious adverse event, fails to comply with the dosing or visit schedule, or withdraws consent.

The investigational product, designated ILT‑101 liquide, contains the active substance aldesleukin, a recombinant form of interleukin‑2. It is supplied as a solution for injection intended for subcutaneous administration. Each dose comprises 1.5 million international units (IU) of aldesleukin, delivered as a single subcutaneous injection on Day 8 of the study.

The comparator is a matched placebo of ILT‑101. The placebo contains no active pharmaceutical ingredient and is presented in a formulation indistinguishable from the active solution. It is administered subcutaneously in an identical volume and schedule to maintain blinding.

Study medication is prepared under aseptic conditions and administered by qualified personnel. Dosing occurs once, with the injection site inspected before and after administration. Compliance is verified by documenting the injection in the source data sheet and confirming receipt of the study drug by the site pharmacy. Any deviation from the prescribed schedule is recorded and reported according to protocol‑specified adverse event and protocol deviation procedures.

The primary efficacy assessment will compare the change in Tregs (expressed as percentage of CD4⁺ cells and absolute count) from baseline to Day 8 between participants receiving ILT‑101 and those receiving placebo. Flow cytometric analysis will be performed on peripheral blood samples collected at Day 0 and Day 8, and the difference will be evaluated using comparative statistical methods.

Secondary efficacy evaluations will incorporate a series of validated clinical instruments and biological assays conducted at baseline (Day 0) and follow‑up visits on Days 85, 169, and 275 (with additional laboratory timepoints on Days 29 and 169 for certain measures). Clinical outcomes include the Vineland‑II Adaptive Behavior Composite (total score, Socialization domain, Communication domain, and Daily Life domain), the Brief Observation of Social‑Communication Change (BOSCC), the Social Responsiveness Scale total score, the Autism Diagnostic Observation Schedule‑2, the Aberrant Behavior Checklist, the ADHD Rating Scale (parent report), the Clinical Global Improvement scale, and the Caregiver Strain Index. Each instrument will be administered by trained evaluators according to standard protocols, and scores will be recorded at the designated visits. Biological secondary endpoints comprise Treg and Th17 assays (percentage of CD4⁺ cells and absolute values) performed at Days 0, 8, 29, 85, 169, and 275, with area‑under‑the‑curve calculations for the intervals Day 0–Day 29 and Day 29–Day 169. Tolerability will be monitored using the Pediatric Adverse Event Rating Scale at Days 0, 8, 85, and 169. All data will be entered into a centralized database, subjected to quality control checks, and analyzed using predefined statistical models to assess treatment effects over time.